1. Field of the Invention
The invention relates to a blade for a turbine rotor, and more particularly the invention relates to a hollow blade for a high-pressure gas turbine, in particular for a helicopter. Nevertheless, the invention is also applicable to engines for airplanes, and more generally to any gas turbine. The invention relates more particularly to a hollow blade of the type having a closed end wall, i.e. in which the end wall does not include an orifice, as contrasted to hollow blades of the type having an open end wall or that are said to be “cooled” and that do not form the subject matter of the present invention.
2. Description of the Related Art
As shown in FIGS. 1 and 2, for a turbine blade 10 extending radially between its root and its blade tip 12, an open cavity 14, referred to as a “bathtub”, is generally provided that is defined by a closed end wall 16 and by a side rim 18. The radial direction R of the blade is relative to the rotor that supports it, the axial direction being the direction of the axis of the engine and is perpendicular to the radial direction. Such a blade conventionally presents a pressure side 24, a suction side 26, a leading edge 28, and a trailing edge 30.
Compared with a blade tip that is solid, the presence of the cavity 14 serves to lighten the blade and to modify the gas flow structure, thereby limiting undesirable flow of gas from the pressure side 24 towards the suction side 26 of the blade. Nevertheless, on flowing into the inside of the cavity 14, hot gas from the combustion chamber situated upstream from the turbine heats the walls of the cavity 14 by convection.